30 years of PCs (slideshow)

The clones

The IBM PC had three vital characteristics: it used a standard, cheap, Intel 8088 processor; it had 62-pin (ISA) expansion slots with standard, well-documented behavior; and most importantly, it used PC-DOS, a proprietary version of MS-DOS that was slightly tweaked by IBM.

In other words, there was very little about the IBM PC that was actually unique — except for the BIOS, which was quickly reverse engineered by companies like Phoenix, Award, and American Megatrends. Once the BIOS was available with an off-the-shelf chip, IBM Compatibles (or PC clones) soon begun to emerge from OEMs like HP, Dell, and Compaq (pictured above is the Compaq Portable, the first PC-compatible computer).

The lynchpin that heralded the arrival of PC Clones (and their subsequent domination of the market), however, was MS-DOS. The IBM PC (and its clones) supported other OSes like CP/M-86, but MS-DOS was considerably cheaper. In theory, if IBM had demanded that PC-DOS was a Microsoft exclusive, PC clones would probably have never taken off. If MS-DOS hadn’t been freely available, there wouldn’t have been a huge market of commodity computers that were capable of running Windows. In short, Microsoft really owes its entire success to the IBM PC and the PC clones.

It’s also worth noting that it wasn’t just IBM PCs being cloned: AMD, NEC, Texas Instruments, and others, were all making processors that x86-compatible and functionally identical to the Intel 8088 used in the first IBM PC.

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